Method for maneuvering a vessel with respect to its station



J. LOVELL Aug. 26, 1969 METHOD FOR MANEUVERIN G A VESSEL WITH RESPECT TOITS STATION Filed April 24. 1968 v INV ENT OR Jar/r Zara-[Z Ysemmesandsemmes ATTORNEY 5 g- 26, 1959 Q J. LOVELL 3,463,114

METHOD FOR MANEUVERING A VESSEL WITH RESPECT TO ITS STATION 2% f4 w w w7 .4 i 67 INVENTOR 745 7454 [4141/ BY smmesandsemmes ATTORNEYS J. LOVELL3,463,114

METHOD FOR MANEUVERING A VESSEL WITH RESPECT TO ITS STATION Aug. 26,1969 5 Sheets-Sheet 5 Filed April 24, 1968 INVENTOR 74!? /d/ BYsemmesandsemmes ATTORNEYS J. LOVELL Aug. 26, 1969 METHOD FOR MANEUVERINGA VESSEL WITH RESPECT TO ITS STATION Filed April 24 1968 5 Sheets-Sheet4 I {NVNTOR 740? /4/// BY semmesandsemmes ATTORNEYS J. LOVELL Aug. 26,1969 METHOD FOR MANEUVERING A VESSEL WITH RESPECT TO ITS STATION FiledApril 24, 1968 5 Sheets-Sheet 5 l NVEN TOR .740? [4/[// BYsemmesandsemmes ATTORNEYS United States Patent US. Cl. 114-230 ClaimsABSTRACT OF THE DISCLOSURE Method for maneuvering a vessel with respectto its station, particularly a method for fending the vesselhorizontally and vertically with respect to a rigid station, such as anoffshore oil well drilling platform. According to the method anextensible boom and suctorial cup assembly mounted upon a station isused to draw a vacuum upon integral portion of a maneuvering vesselfreeboard. The boom is raised and lowered in horizontal alignment withthe maneuvering vessel prior to drawing of the vacuum and is supportedfor free vertical movement corresponding to boat action after drawingthe vacuum. The boom is telescoped with respect to the station, so as tocontrol movement of the vessel about the station through the boom.

CROSS-REFERENCE TO RELATED APPLICATIONS None.

BACKGROUND OF THE INVENTION Field of the invention A great deal ofdifficulty has been experienced in maneuvering a work boat with respectto a station such as an offshore drilling rig. This difficulty iscompounded when the working platform of the rig is considerably elevatedwith respect to sea level. The distances involved preclude ready use ofconventional fending devices. As a result, injury both to the rig and tothe work boat is such that offshore drilling rigs prefer service andresupply via the less accident prone method of helicopter.

An effective method for fending a work boat with respect to its station,such as a canal lock or offshore drilling rig in any type of sea has notbeen devised. A primay requirement of such a method would be itscapability of horizontal and vertical flexibility, so as to permitmovement of the Work boat vertically with the sea and horizontally withrespect to an offshore oil rig and enable servicing by a crane or thelike. A secondary requirement would be in the rigidness and reliabilityof the fending so as to preclude injury to its station. Additionalrequirements of the method reside in its capability of quick,remote-controlled disengagement from the vessel, as well as thecapability of absorbing shock.

Description of the prior art Assignee of the present invention hasobtained the following patents issued on related methods and devices:Method and Apparatus for Maneuvering Ships (Pat. No. 3,322,091); ShipManeuvering Method (Pat .No. 3,345,971).

According to both methods, an extensible boom with a suctorial cup isused to position or maneuver one vessel with respect to another. Avacuum is drawn within the cup and through the boom, the cup beingplaced against the freeboard of a vessel being maneuvered. In the3,322,091 patent the telescoping boom and cup may be mounted upon a tug,the cup being attached to the freeboard of a larger vessel. In the3,345,971 patent the extensible boom and suctorial cup include aresupply conduit for the supply of gasoline or the like via pumpingthrough a conduit extending through the extensible boom and cup. Neitherpatent teaches modes of vertically adjusting the entire boom assembly,of employing a plurality of suctorial cups at spaced positions on thefreeboard of the vessel being maneuvered, of positioning the device on arigid station or of shock absorbing the device with respect to thevessel being maneuvered.

SUMMARY OF THE INVENTION Applicants method for station keeping involvesa plurality of extensible boom and suctorial cup devices, so as toposition or fend a work boat with respect to its station. Once thevacuum is drawn through the boom and the suctorial cups, the boom isreleased vertically so as to be movable with respect to swells in thesea and corresponding movement of the work boat. Maneuvering isterminated by breaking of the vacuum, resulting in a disengagement ofthe extensible boom with the vessel being maneuvered. Refinements of themethod consist in pneumatically shock absorbing the boom assembly,supporting the boom for free vertical movement, while limiting lateralmovement of the boom, with respect to its station.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a workboat being maneuvered with respect to an offshore drilling rig by a pairof extensible booms;

FIG. 2 is a top plan, partially in section, showing a single extensibleboom and suctorial cup assembly;

FIG. 3 is a side elevation of the assembly;

FIG. 4 is a sectional view, taken along section line 4-4 of FIG. 2;

FIG. 5 is a sectional view taken along section line 5-5 of FIG. 3;

FIG. 6 is a fragmentary vertical section of the telescoping boom endfitting within its housing;

FIG. 7 is a sectional view taken along section line 77 of FIG. 6;

FIG. 8 is a sectional view taken along section line 88 of FIG. 6;

FIG. 9 is a front elevation of the vertically movable steel truck 26supporting boom and suctorial cup elements 83 and FIG. 10 is a likefront elevation with the extensible boom and suctorial cups removed;

FIG. 11 is an enlarged side elevation, partially in section, showing thedish 36 and skirt 104 defining vacuum chamber 112 in the suctorial cupassembly;

FIG. 12 is an enlarged fragmentary section of the suctorial cup skirtelement;

FIG. 13 is a fragmentary perspective, showing installation of a proposedstation keeping device within a canal lock so as to assist in locking ofthe vessel;

FIG. 14 is a fragmentary end elevation, showing the FIG. 13 devicewherein the truck 26 containing suctorial cups 88', 90', 92' and 94 islifted above the lock upon inclined tracks 16 and 18' when not in use,tracks 16' and 16 being set or recessed Within the concrete lock wallswhen parallel to the vessel freeboard;

FIG. 15 is a fragmentary front elevation of truck 26' containing thesuctorial cups;

FIG. 16 is a fragmentary top plan thereof with the suctorial cups inretracted position; and

FIG. 17 is a top plan thereof with the suctorial cups in extendedfreeboard engaging position.

3 DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a station keepingdevice generally designated as 2 is shown vertically movably positionedin offshore drilling rig platform 6 by means of vertical channels ortracks 16, 18, 20 and 22 secured to the rig superstructure 24.

The station keeping device includes a pair of like extensible boomassemblies 12 and 14 having at their respective ends suctorial cups 88,90, 92-94 engaging the freeboard of work boat vessel 4.

A suggested assembly for carrying out the method is illustrated in FIGS.2, 3, 9 and 10 as comprising truck 26 vertically movable in tracks 16and 18 by means of radially extending rollers 28, 30, 32 and 34 mountedrespectively in radially extending arms 36, 37, 38 and 39, secured atthe corners of the truck assembly 26. Additionally, top rollers 40, 42,lower middle rollers 44, 46 and bottom rollers 48, 50 may be positionedat the truck sides at right angles to the corner rollers 28, 30, 32 and34. Rollers 40, 42, 46, 48 and 50 engage the interior walls of track orchannels 16 and 18.

The extensible boom assembly 12 is more particularly illustrated inFIGS. 2 and 3, as comprising housing 52 secured pivotably at one end totruck 26 by means of ears 56 engaging lugs 58 and secured thereto bymeans of pin 60. Extensible piston rod 54 is supported rotatably withinthe housing 52 by means of outer rollers 114 and 116 mounted,respectively, upon pins 118 and 120 supported in housing 52 and innerrollers 122 and 124 secured on piston 54 inner end by means of pins 126and 128. Stops or lugs 130 and 132 secured respectively to the interiorwall of housing 52 and the exterior of piston 54 may be positioned forlimiting horizontal extensibility of rod 54.

A pneumatic shock absorber assembly housing 70 supplied by air line 64includes extensible piston rod 82 secured to piston 54 by means of ear78 and pin 80 at one end and secured to housing 52 by means of ears 72,74 and pin 76 at the other end. Piston rod 54 is extended horizontallyby means of hydraulic fluid fed through supply line 62.

Piston rod 54, as illustrated in FIGS. 2 and 3, terminates in clevisassembly 138 which movably supports yoke 134 by means of pin 136. Ateither end of yoke 134, suctorial cups 88 and 90 are universally mountedby means of brackets 144 and 146, secured by identical pins 140 and 142.The cups 88 and 90 include rear brackets 98 and 98 secured respectivelyto brackets 144 and 146 by pins 148 and 150.

Each suctorial cup consists of dish 96, outer or peripheral rubber orneoprene skirt 104 defining an inner vacuum chamber 112, vacuum beingdrawn through interiorally threaded conduit 102 by means of vacuumfitting 100 to which the vacuum lines 112 and 112 may be secured. Skirt104 may include inner serrations 106, middle flange 110 and outerperipherally extending flange 108, the serrations and flanges enablingthe cup to seal with respect to the irregularities of the work boatfreeboard.

The boom may be rigidized with respect to truck 26 by means ofvertically extending strut 68, secured to the truck by means of lug 66,and laterally extending strut 84, secured to truck 26 by means of lug86.

In FIG. 1 control house 10 is generally illustrated as including awinch, such as a 5,000 pound constant tension winch used to positionvertically the extensible booms 12 and 14 prior to engagement of thework boat freeboard and drawing of the vacuum. Drawing of the vacuumthrough the cup assembly may be accomplished by a ten horsepower 177cubic foot per minute 29 inches mercury vacuum device having a 15 cubicfoot vacuum tank. The hydraulic system for extending and retractingpiston rods 54 may include a g.p.m. at 1,500 p.s.i., two to three gallonpiston accumulator for shock absorption. A steel lifting cable 50 may besecured to truck 26 by means of bracket 48 for lifting of the assemblyprior to drawing of the vacuum.

The suctorial cups may be approximately 4 square feet, each developing10 p.s.i. (5 p.s.i.a.) vacuum. Such a suctorial head would have aholding capability of 5,760 pounds or assuming that two extensible boomswith four cups were employed a total of 23,040 pounds for four cups in adirection transverse to the work boat keel. Holding capability parallelto the boat keep would be approximately based on the friction forcedeveloped between the suctorial cup and the boat hull. In a proposedextensible boom assembly, as illustrated in FIGS. 2 and 3, the boomassembly may be eight feet retracted, eleven feet in its holdingposition and twelve feet in its extended position.

In operation, work boat 4 would achieve its station with the booms 12and 14 in retracted position. The booms would be vertically adjusted bymovement of trucks 26 by cables 50 and the individual piston rods 54extended hydraulically to contact the work boat freeboard. Vacuum wouldbe drawn through the cups 88, 90, 92 and '94, the vacuum systemoperating continuously to hold a 5 p.s.i. to 14.7 p.s.i. vacuum on thework boat. Winch 50 could be automatically disengaged by a device forsensing the drawn vacuum. As the booms 12 and 14 are extendedhydraulically to eleven feet in length, two hydraulic accumulators couldbe cut into the circuit, one at each end .of the hydraulic rams 12 and14 to give an air spring load absorption. Disengagement of the suctorialcups could be instantly accomplished by breaking the vacuum throughcontrol lines 112. Disengagement due to overload would be automatic asthe work boat could break away from the cups without power failure bysimply breaking the vacuum at seal 104.

According to the FIGS. 13-17 adaptation truck 26 front is liftedvertically by means of cables 50 extending to a power winch with housing10. The entire truck is shown in stowed position in FIG. 14. The midships truck 26 includes a horizontal track 216, attached to cable 50',which enables the truck 26' to travel horizontally approximately 40 feetin order to position the ship and start the ship in motion.

Truck 26 is essentially similarly constructed as in the basic devicewith radially extending track engaging wheels 28', 30, 32' and 34', aswell as top rollers 40' and 42 and bottom rollers 48' and 50. Theindividual suctorial cups are mounted upon a pair of identical yokes 134to which gate 212 is attached by means of pins 214 and 215. A hydraulicpower assembly 206 is connected to truck 26 by means of pin 218 andincludes piston 208, having an end clevis 210, engaging pin 215. As thehydraulic cylinder is actuated so as to distend piston 208, the entireyoke 134 is distend outwardly of the lock wall and against the vesselfreeboard 4, as illustrated in FIG. 17.

As suggested in FIG. 13, twenty-four suctorial cups may be employed,twelve on each side of the vessel. In such an arrangement each truckcould develop a force capability of 54,000 pounds transverse to thelock, three such trucks developing a force capability of 162,000 poundstransverse to the lock on each side of the vessel, based upon the use of3 foot square suctorial paths. Conventional commercial vacuum hydraulicsystems and hydraulic winches may be employed. There is no necessity forreduction in the lock width, inasmuch as individual rails 16' and 18 arerecessed in the concrete walls. It is estimated that an operation cyclewould be one minute consisting of fifteen seconds to lower the truck onthe rail to position opposite the freeboard, fifteen seconds to gate thecups onto the freeboard, as illustrated in FIG. 17, fifteen seconds toeffect vacuum attachment and fifteen seconds for inspection.

Manifestly, the extensible boom and vertically movable truck assembliesmay be varied, for example by mounting on a vessel, without departingfrom the spirit and scope of invention.

I claim:

1. Method for maneuvering a vessel with respect to its stationcomprising the steps of:

(A) horizontally telescoping a rigid boom and suetorial cup, which ismounted upon the boom end for universal movement, with respect to saidstation, so as to contact said vessel;

(B) raising and lowering said boom in horizontal alignment with saidvessel;

(C) ditferentiating pressure between ambient and an integral portion ofsaid vessel which is in contact with said station by means of said rigidboom and suctorial cup by drawing a vacuum through said suctorial cup;

(D) supporting said boom for free vertical movement corresponding toboat action, as said vacuum is drawn;

(E) shock absorbing said boom by fluid means; and

(F) controlling movement of said integral portion of said vessel aboutsaid station through said boom.

2. Method for maneuvering a vessel with respect to its station as inclaim 1, including distending said boom with respect to said station.

3. Method for maneuvering a vessel with respect to its station as inclaim 2, including drawing a vacuum within a plurality of spacedintegral portions of said vessel in contact with said station via aplurality of rigid booms.

4. Method for maneuvering a vessel with respect to its station as inclaim 3, including limiting lateral movement of said boom within saidstation, while supporting said boom for free vertical movement.

5. Method for maneuvering a vessel with respect to its station as inclaim 4, including breaking said vacuum as a termination of controllingmovement of said vessel.

References Cited UNITED STATES PATENTS 2,920,597 1/1960 Dick 114-2303,322,091 5/ 1967 Stanwick 114235 FOREIGN PATENTS 797,653 7/ 1958 GreatBritain.

TRYGVE M. BLIX, Primary Examiner

